From 4ee92d9d9d2e3b6ea89005cd95c0f165de2d03b4 Mon Sep 17 00:00:00 2001
From: Laurent Mazet <mazet@softndesign.org>
Date: Mon, 2 Jan 2023 23:29:22 +0100
Subject: [PATCH] add precision

---
 calc.c     | 17 ++++++++++++++++-
 fdprintf.c |  7 ++++---
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/calc.c b/calc.c
index e255bd2..95eef4e 100644
--- a/calc.c
+++ b/calc.c
@@ -26,6 +26,7 @@
 /* gobal variables */
 
 char *progname = NULL;
+int precision = 6;
 
 /* help function */
 
@@ -34,6 +35,7 @@ int usage (int ret)
     int fd = ret ? stdfderr : stdfdout;
     fdprintf (fd, "usage: %s\n", progname);
     fdprintf (fd, " -h : help message\n");
+    fdprintf (fd, " -p : precision (%d)\n", precision);
     fdprintf (fd, " -v : verbose level (%d)\n", verbose);
 
     return ret;
@@ -70,6 +72,14 @@ int main (int argc, char *argv[])
         }
         char c = arg[1];
         switch (c) {
+        case 'p':
+            arg = (arg[2]) ? arg + 2 : (--argc > 0) ? *(++argv) : NULL;
+            if (arg == NULL) {
+                PRINTERR ("%s: missing precision\n", progname);
+                return usage (1);
+            }
+            precision = atoi (arg);
+            break;
         case 'v':
             arg = (arg[2]) ? arg + 2 : (--argc > 0) ? *(++argv) : NULL;
             if (arg == NULL) {
@@ -83,6 +93,10 @@ int main (int argc, char *argv[])
             return usage (c != 'h');
         }
     }
+    
+    /* format */
+    char format[8] = "=> %.f\n";
+    format[4] = '0' + precision;
 
     /* read from input stream */
 
@@ -104,7 +118,7 @@ int main (int argc, char *argv[])
                     ret = 1;
 		        } else {
                     VERBOSE (INFO, print_element (element, 0));
-                    PRINTOUT ("=> %f\n", evaluate_element (element, 0));
+                    PRINTOUT (format, evaluate_element (element, 0));
                     delelement (element);
                     ret = 0;
                 }
@@ -174,5 +188,6 @@ int main (int argc, char *argv[])
 // test: echo "2 + * 3" | calc.exe | grep -q 'error'
 // test: echo "sqrt 2" | calc.exe | grep -q 'error'
 // test: echo "pow (2)" | calc.exe | grep -q 'error'
+// test: echo "1.23456789" | calc.exe -p 3 | grep -q '1\.234'
 
 /* vim: set ts=4 sw=4 et: */
diff --git a/fdprintf.c b/fdprintf.c
index 76722fc..17b8473 100644
--- a/fdprintf.c
+++ b/fdprintf.c
@@ -137,13 +137,14 @@ int fdprintf (int fd, const char *fmt, ...)
                     *str++ = '-';
                     f = -f;
                 }
-                t = getexponant (&f, -6);
+                if (sz == 0) sz = 6;
+                t = getexponant (&f, -sz);
                 u = (int)f;
                 str = itoa (str, u, 0);
-                d = (int)((f - u) * tenpower (6));
+                d = (int)((f - u) * tenpower (sz));
                 if (d > 0) {
                     *str++ = '.';
-                    str = itoa (str, d, 6);
+                    str = itoa (str, d, sz);
                 }
                 while (*(str - 1) == '0') {
                     str--;
-- 
2.30.2